Centro de astrobiología asociado al NASA Astrobiology Institute

Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?10-09-2015 CAB IN THE MEDIA (Scientfic Reports-Nature)

An article about the origin of river erosion channels on Mars entitled "Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?" was published in Scientific Reports section of the journal Nature. Alberto González Fairén, a researcher in the Department of Planetology and Habitability of the Centro de Astrobiología (CAB, CSIC-INTA), is part of the international team that conducted the study.

Catastrophic floods generated ~3.2 Ga by rapid groundwater evacuation scoured the Solar System’s most voluminous channels, the southern circum-Chryse outflow channels. Based on Viking Orbiter data analysis, it was hypothesized that these outflows emanated from a global Hesperian cryosphere-confined aquifer that was infused by south polar meltwater infiltration into the planet’s upper crust. In this model, the outflow channels formed along zones of superlithostatic pressure generated by pronounced elevation differences around the Highland-Lowland Dichotomy Boundary. However, the restricted geographic location of the channels indicates that these conditions were not uniform Boundary. Furthermore, some outflow channel sources are too high to have been fed by south polar basal melting. Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which was then completely submerged under a primordial northern plains ocean. Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region. Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation.